Using anonymous functions inside functions

I was reading an article on Javascript and its use of first class functions. I'd quote it if I could find it again, but basically, it extolled the virtues of being able to create anonymous functions, blocks, and closures easily in Javascript. One of the things that it claimed was that creating local functions only used within a method makes the code much more readable. I was skeptical, but as I was refactoring this function, I thought I'd give it a shot even though I was coding in Ruby. Ruby also allows for the creation of first class functions.

It's just a helper function that generates a bookmark button--however, what gets generated depends on whether a user is logged in and whether a user had already bookmarked the page.

  def bookmark_button(page, user, indicator_id)
    if page.bookmarked_by? session[:user]
      "Bookmarked!"
    elsif page.done_by? session[:user]
      link_to_remote image_tag('heart_add.png', :height => 16, :width => 16) + " Bookmark again!", 
                               :url => { :controller => :bookmark_list, :action => :add, :page_id => page.id  }, 
                               :loading => "Element.toggle('#{indicator_id}')", 
                               :complete => "Element.toggle('#{indicator_id}')"
    else
      link_to_remote image_tag('heart_add.png', :height => 16, :width => 16) + " Bookmark!", 
                               :url => { :controller => :bookmark_list, :action => :add, :page_id => page.id  }, 
                               :loading => "Element.toggle('#{indicator_id}')", 
                               :complete => "Element.toggle('#{indicator_id}')"
    end
  end

Well, I thought it was pretty straightforward to read, though half of it was duplicated code. It wasn't very DRY. So instead of fudging around with another way to structure the control flow, I tried my hand at using blocks. I ended up with this:

  def bookmark_button(page, user, indicator_id)
    bookmark_link = Proc.new { |label| 
      link_to_remote "#{image_tag('heart_add.png', :height => 16, :width => 16)} #{label}", 
                     :url => { :controller => :bookmark_list, 
                               :action => :add, 
                               :page_id => page.id  }, 
                     :loading => "Element.toggle('#{indicator_id}')", 
                     :complete => "Element.toggle('#{indicator_id}')"
    }

    if page.bookmarked_by? session[:user]
      "Doing this"
    elsif page.done_by? session[:user]
      bookmark_link.call("Bookmark again!")
    else
      bookmark_link.call("Bookmark!")
    end
  end

As you can see, I put the link_to_remote() code into a block, since the only difference between the two is the label. In addition, it is possible for the block to use variables that are in this method, but outside the block, even if the execution is outside the scope of this function, if the block is ever passed outside of bookmark_button. I know in javascript, this causes memory leaks in IE. I haven't heard that it's a problem in Ruby yet.

But in this case, I'm just creating a function inside a method to make things more readable and cleaner. I think for the most part, it worked pretty well. As long as it's not overdone (notice I didn't create a proc for the labels), it should make for more readable code, and you don't pollute the class namespace with methods that are only used in this one method. I should get use to this. tip!